AD 98-01-01

98-01-01 CESSNA AIRCRAFT COMPANY: Priority Letter issued on December 22, 1997. Docket No. 97-CE-150-AD.

Applicability: The following airplane models and serial numbers, certificated in any category:

Model 172R Airplanes: serial numbers 17280003 through 17280171, 17280173 through 17280175, 17280177 through 17280179, 17280182 through 17280184, 17280186, 17280189, 17280190, 17280192 through 17280212, 17280214, 17280216 through 17280221, 17280223 through 17280236, 17280239 through 17280251, 17280253 through 17280263, 17280265, 17280268, 17280270 through 17280272, 17280283, 17280297, and 17280301; and

Model 182S Airplanes: serial numbers 18280001, 1820002, 18280004 through 18280045, 18280048 through 18280060, 1820062 through 18280064, 18280067, and 18280070.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (h) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

Compliance: Required as indicated in the body of this priority letter AD, unless already accomplished.

To prevent erroneous indications from the altimeter, airspeed, and vertical speed indicators, which could cause the pilot to react to incorrect flight information and possibly result in loss of control of the airplane, accomplish the following:

(a) Prior to further flight after receipt of this priority letter AD, fabricate placards with the following words, using letters at least 1/8-inch in height, and install these placards in the cockpit within the pilot s clear view:

(1) "IFR operation is prohibited."

(2) "Use of the alternate static air source is prohibited."

(b) Within the next 100 hours time-in-service (TIS) after receipt of this priority letter AD or within the next 4 calendar months after receipt of this priority letter AD, whichever occurs first, inspect the alternate static air source valve to assure that the alternate static air source valve is not restricted by the identification placard and to assure that the valve body does not separate from the valve flange in accordance with Cessna Service Bulletin No. SB97-34-02, Revision 1, dated December 22, 1997.

(1) If the alternate static air source valve is restricted, prior to further flight after the inspection required by paragraph (b) of this AD, rework the alternate static air source assembly in accordance with Cessna Service Bulletin No. SB97-34-02, Revision 1,dated December 22, 1997.

(2) If the valve body separates from the valve flange, replace the alternate static air source assembly in accordance with the maintenance manual at one of the compliance times presented below (paragraph (b)(2)(i) or (b)(2)(ii) of this AD):

(i) Prior to further flight to eliminate the operating limitations required by the placards in paragraphs (a), (a)(1), and (a)(2) of this AD; or

(ii) Within the next 25 hours TIS after the inspection provided the operating limitations required by the placards in paragraphs (a), (a)(1), and (a)(2) of this AD are adhered to.

(c) The placard requirements of paragraphs (a), (a)(1), and (a)(2) of this AD may be eliminated when the inspection, rework, and replacement requirements are accomplished as specified in paragraphs (b), (b)(1), and (b)(2) of this AD.

(d) The inspection, rework, and replacement requirements specified in paragraphs (b), (b)(1), and (b)(2) of this AD may be accomplished at any time prior to "within the next 100 hours TIS after receipt of this priority letter AD or within the next 4 calendar months after receipt of this priority letter AD, whichever occurs first."

(e) Within 10 days after the inspection required by paragraph (b) of this AD, send the results of the inspection in writing to the FAA at the address specified in paragraph (h) of this. Include the serial number of the airplane and state whether the alternate static air source assembly needed to be reworked or replaced. (Reporting approved by the Office of Management and Budget under OMB No. 2120-0056).

(f) Fabricating and installing the placards as required by paragraph (a) of this AD may be performed by the owner/operator holding at least a private pilot certificate as authorized by section 43.7 of the Federal Aviation Regulations (14 CFR 43.7), and must be entered into the aircraft records showing compliance with this AD in accordance with section 43.9 of the Federal Aviation Regulations (14CFR 43.9).

(g) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(h) An alternative method of compliance or adjustment of the compliance times that provides an equivalent level of safety may be approved by the Manager, Wichita Aircraft Certification Office (ACO), 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Wichita ACO.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Wichita ACO.

(i) Copies of the applicable service information may be obtained from the Cessna Aircraft Company, Product Support, P.O. Box 7706, Wichita, Kansas 67277; telephone: (316) 941-5800; facsimile: (316) 942-9006. This information may also be examined at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.

(j) Priority Letter AD 98-01-01, issued December 22, 1997, becomes effective immediately upon receipt.

98-01-01 Cessna

Events Leading to This Priority Letter
The Federal Aviation Administration (FAA) has received reports of improper installation of the identification placard on the alternate static air source. This placard was installed on the valve body in a location that covers the external orifice, which is the inlet for static air reference into the valve.

Cessna discovered the problem during a preflight static check on a Model 172R airplane. Further investigation and a purge of stock at the manufacturing facility revealed 21 valve assemblies having the identification placard installed over the static air reference orifice. Cessna has no way of verifying how many of these assemblies were manufactured and sent to the field with the identification placard installed over the static air reference orifice.

Several of these assemblies have been identified and corrected on the above-referenced airplanes. The FAA has no way of determining which airplanes have the remainingproblem alternate static air source assemblies installed without having all of the affected airplanes inspected.

These assemblies are required for flight into instrument flight rules (IFR) conditions as defined in section 91.411 of the Federal Aviation Regulations (14 CFR 91.411). Use of these assemblies is optional in visual flight rules (VFR) conditions.

If these assemblies are not identified and reworked or replaced, selection of the alternate air source will cause the altimeter, airspeed, and vertical speed indicators to display erroneous indications. This could cause the pilot to react to incorrect flight information and possibly result in loss of control of the airplane.

Relevant Service Information
Cessna has issued Service Bulletin No. SB97-34-02, Revision 1, dated December 22, 1997, which includes:

- procedures for inspecting the alternate static air source valve to assure that the alternate static air source port is not restricted by the identification placard and to assure that the valve body does not separate from the valve flange;

- procedures for reworking the alternate static air source valve if the port is restricted; and

- reference to replacing the alternate static air valve assembly if the valve body separates from the valve flange in accordance with the maintenance manual.

Cessna is providing warranty credit for both labor and parts for required inspections, reworks, and replacements.

The FAA s Determination
After examining the circumstances and reviewing all available information related to the situation described above, including the service information previously referenced, the FAA has determined that AD action should be taken to prevent erroneous indications from the altimeter, airspeed, and vertical speed indicators, which could cause the pilot to react to incorrect flight information and possibly result in loss of control of the airplane.

Explanation of the Provisions of This Priority Letter ADSince an unsafe condition has been identified that is likely to exist or develop on other Cessna Models 172R and 182S airplanes of this same type design, the FAA is issuing a priority letter AD. This priority letter AD requires the following:

- immediately fabricating placards that prohibit operation in IFR conditions and prohibit use of the alternate static air source, and installing these placards in the cockpit within the pilot s clear view;

- eventually inspecting the alternate static air source valve to assure that the alternate static air source port is not restricted by the identification placard and to assure that the valve body does not separate from the valve flange;

- reworking the alternate static air source assembly if the port is restricted; and

- replacing the alternate static air source assembly if the valve body separates from the valve flange.

Accomplishment of the inspection and rework is required in accordance with the previously referencedservice information. Accomplishment of the replacement is required in accordance with the applicable maintenance manual.

The AD
This rule is issued under 49 U.S.C. Section 44701 (formerly section 601 of the Federal Aviation Act of 1958), pursuant to the authority delegated to me by the Administrator, and is effective immediately upon receipt of this priority letter.